When I set up 11 Dutch buckets of kale, collard greens, broccoli and Swiss chard in my greenhouse last summer, I thought I might have a few greens to harvest for a couple of months in the winter. Now, 10 months later, I'm still harvesting from what I call my greens machine, and the setup has produced a continuous output of fresh produce with a surprising total value.
The greens began to mature by October. Since then, I've picked the equivalent of two grocery-store bundles a night, at least five times a week. At $3 per bundle, that's about $1,200 not spent at the grocery store.
After 10 months, I'm still harvesting from what I call my greens machine, and the setup has produced a continuous output of fresh produce.
The setup takes up about 36 square feet in a 3-by-12-foot section of my greenhouse, and requires no expertise or special tools to build.
Each bucket is about a foot wide, half the size of a plastic 5-gallon paint bucket, with a single drain at the bottom. The buckets are set side by side, along the north wall of the greenhouse, elevated off the ground by a shelf to make harvesting easier.
A mixture of coconut coir and perlite forms the growing medium in each bucket. An irrigation tube runs along the top of the buckets and drips water and nutrients into the medium, right at the roots of the greens. The nourishing water solution is pumped from the collection container to the irrigation tubing by a small water feature pump.
For drainage, a PVC pipe runs horizontally underneath the buckets. The pipe has holes big enough that the drain of each bucket can fit into the hole and allow overflow to drain into the pipe. Drilling holes into the pipe was the only carpentry skill I needed. The drainage flows into the pipe, and that channels into a large container that holds about 25 gallons.
So the water flows from that container into each bucket, drips into the PVC pipe and channels back to the container from which it came. This is hydroponics. This closed-loop way of circulating water reduces consumption in crops to about a quarter of what it takes to grow them in the soil.
The setup is inexpensive in view of the return it offers. To estimate its cost, I've accounted for the following:
- $70 for 11 Dutch buckets
- $20 in PVC piping
- $10 for drip irrigation tubing
- $30 for a small, submersible water feature pump
- $15 for a large plastic storage container, used for a reservoir
- $100 in electricity, an overestimate as the pump uses about the wattage of CFL light for only a few minutes each cycle, five times each day
- $10 for a timer, to cycle the pump
- $25 for an aquarium air pump and air stone, to aerate the water
- $60 for nutrients (GroMagnon from American Hydroponics), shared with several other hydroponic crops I've grown at the same time
- $30 in coconut coir and perlite for the growing medium
- $5 in seeds
- $187 for the greenhouse space, amortized
The total is $562. Subtracting from the $1,200 I've saved, that leaves $638 as the return I've cleared. The pump, piping and buckets will last for several years, maybe even a decade, which means that the crop paid for everything it takes to grow it in the first year and still brought several hundred dollars' worth of savings on my food bill.
Every year that I use this equipment will result in an even higher return. My costs in subsequent years will only be for seeds, nutrients, electricity and the amortized cost of the greenhouse. Even the growing medium is reusable.
The plants transpire water, so I have to top off the reservoir every day with about two gallons of fresh, pure rainwater. This is an average, though, because I needed to top off the reservoir with only about two or three gallons in a week when the days were overcast for the last two months. Now that summer heat is returning, I add about four gallons every day.
As for taste, the selections I've been growing have never had even a hint of the bitterness that often afflicts greens.
I've not included water use in the expenses because I can't begin to estimate the amortized cost of the rainwater collection system my father built. But even if I had been forced to use filtered, reverse osmosis water at 35 cents per gallon from the coin-operated dispensers at the local health food store, I'd have spent about $196 over the last 40 weeks and would have still cleared $400 in savings.
What's more, the quality of the harvest beats anything I've ever found, making the misted bundles in the produce aisle seem like limp, leathery clumps of sorry vegetable matter by contrast. What I pick, minutes before it's steamed or sautéed, is a harvest of greens so crisp that it's fragile.
If I take a leaf of my Dwarf Blue Curled Scotch kale and try to bend it, it snaps and breaks clean into two pieces with no resistance. Pop it fresh into your mouth, and it crunches only briefly before it falls apart. I can't compare its texture to anything else because it's unique. It's a tender green with what seems like a cool, liquid-filled center. I have to harvest these greens carefully or the leaves will fall apart.
As for taste, the selections I've been growing have never had even a hint of the bitterness that often afflicts greens. Even though the season has been cooler than normal with more overcast days than not, the sun has shined, and the greenhouse has gotten hot.
Yet these greens, bathed in a flow of cool water that flows frequently over their roots, have stood up to the heat without developing the acrid flavors that heat usually produces in such crops. The flavor of each crop is uncomplicated. Compared to soil-grown greens, the taste is somehow cleaner, with less aftertaste. These are vintage greens, and I imagine that anyone who's ever said he doesn't like greens could be won over easily by a sample of these.
These greens are grown in an insect-proof greenhouse, which may be what has spoiled my wife and me the most: They're ready to eat, raw or cooked, straight from the plant. No soil residue splashed up onto the leaves by a recent rain shower, no colony of aphids gorging themselves on the plant juices of every leaf I've picked. No spider egg sacks, lady bug larva or praying mantises that need to be picked off and returned to the garden.
There's also no reason for us to go without greens, because they can't get knocked down by adverse weather. As I tend flowers and houseplants I'm growing in the greenhouse, it's tempting to pick a leaf and snack on it straight from the plant, which I do occasionally.
We eat greens not only because they're tasty, but also because they are our primary source of calcium, vitamin A and other key nutrients. Greens are so nutritious that I wonder if the fact that I've not yet needed cataract surgery after my vitrectomy last December has anything to do with the copious quantities of lutein and zeaxanthin I get from my crop. These two nutrients are associated with a lower cataract risk because of their antioxidant qualities.
Now that summer is almost here and temperatures during the day in the greenhouse are reaching the high 90s, I don't expect the greens to thrive much longer. It's pushing it to grow these crops outside of late fall through early spring. That they've held out as long as they have is due to the cooler season we've had this year and the perfect growing conditions that hydroponics creates for plants.
If my greens machine continues to produce edible greens through June, it'll be almost a year that I've harvested such premium produce just about every day. I'll start a new crop in August, after which the harvest should start up again in late September and give me another reliable supply of nutritious, clean and delicious greens until next summer.
An electroconductivity meter measures the amount of nutrients in the water that flows into the Dutch buckets.
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